Bernard's experiments show how the milky chyle released from the pancreas dissolves the fat into a minutely divided state.
A treatise on the function of digestion; its disorders, and their treatment by Pavy
The next office of the pancreatic juice to be spoken of is that connected with the digestion of fat. Eberle, it appears, was the first to announce, which he did as far back as 1834, that the pancreas possessed the power of emulsifying fat. He experimented, however, only with the glandular tissue of the organ, and never obtained its secretion. His annoucement also could not have received much attention, as it is not until after the publication, in 1848, of Bernard's extensive series of experiments, commenced in 1846, of Bernard's extensive series of experiments, commenced in 1846, that hte pancreas is found to be spoken of by physiologists in connection with the digestion of fat. Before Bernard's researches nothing was known about the nature of the pancreatic secretion, and nothing had been shown to connect it with the digestion of fat. Bernard is therefore fairly entitled to the credit of discovering the function of the pancreas now about to be referred to.
It appears that Bernard was led to the prosecution of his researches upon this subject through observing, whilst conducting some experiments for the purpose of comparing the phenomena of digestion in the animal and vegetable feeder, that after the ingestion of fat the lacteals coming from the intestine almost up to the pylorus were found to be injected with milky chyle in the dog, whilst in the rabbit chyle only made its appearance in the lacteals some little distance down. With this, he noticed a corresponding difference in the point of discharge of pancreatic juice into the intestine, and thus was prompted, whilst seeking for an explanation of the phenomenon, to give attention to the pancreas. In this manner he was led to endeavor to collect the pancreatic juice, and, having succeeded in this, to examine its action upon fat.
The effect produced when pancreatic juice is freely shaken with oil or fat is to form a liquid having the appearance of milk. The pancreatic juice emulsifies or brings the fatty body into a minutely divided state; in which it afterwards remains suspended in the liquid in the same manner as is noticed in milk. The minute globules into which the fat has been separated have no disposition again to coalesce and rise and form an oily layer at the surface, as they do when saliva or any ordinary watery liquid may happen to have been used instead. In this state of minute subdivision the fatty matter is found to be adapted for absorption and passage into the lacteals, the effect of its presence in the lacteals being to give to the contents a milky character, which they do not possess when no absorption of fat is going on.